Jet propulsion nozzles



JET PROPULSION NOZZLES 7 sheets-sheet 1 Filed Sept. 25, 1961 T. E. G. GARDINER ETAL. 3,134,226

May 26, 1964 y JET PROPULSION NOZZLES '7 Sheets-Sheet 2 Filed Sept. 25, 1961 May 26, 1964 T. E. G. GARDINER ETAL 3,134,226

JET PRoPuLsIoN NozzLEs Filed Sept. 25, 1961 '7 Sheets-Sheet 3 v By I* v MM2) Aurl'neyy y May 26, 1964 T. E. G. GARDINER ETAL 3,134,226

JET PRoPuLsIoN NozzLEs Filed Sept. 25, 1961 '7 Sheets-Sheet 4 Inventor.

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May 26, 1964 T. E. G. GARDINER ETAL 3,134,225

JET PRoPuLsIoN NozzLEs Filed Sept. .25, 1961 7 Sheets-SheerI 5 92 sala 113/@ 76 l/g. 6'.

A (torn e yS May 26, 1964 T. E. G. GARDINER ETAL 3,134,226

JET PROPULSION NOZZLES 7 Sheets-Sheet 6 Filed Sept. 25, 1961 May 26, 1964 T. E. G. GARDINER ETAL 3,134,226

JET PRoPuLsIoN NozzLEs Filed Sept. .25, 1961 7 Sheets-Sheet 7 UnitedStates Patent() 3,134,226 JET PRGPULSION NOZZLES Terence Edward Gonvent Gardiner and Philip William Davis, Bristol, England, assignors to Bristol Siddeley Engines Limited, Bristol, England, a British company Filed Sept. 25, 1961, Ser. No. 140,587 Claims priority, application Great Britain Sept. 29, 1960 S Claims. (Cl. 6ft-35.54)

This invention relates to jetupropulsion nozzles which are adjustable to vary the nozzle area and to reverse the direction of discharge for braking purposes.

According to the invention, a jet propulsion nozzle includes fixed structure, and a pair of opposing fiaps which define between them a nozzle passage leading to a rear outlet, and which are mounted in the fixed structure, to pivot each about an upstream axis to vary the crosssectional area of the nozzle passage, and also to pivot each about a downstream axis to reach a position in which they define with the fixed structure a pair of opposing lateral outlets from the nozzle passage for the discharge of a gas flow in a direction having a component the reverse of rearward, and in which they close the rear outlet between them.

Examples of nozzles according to the present invention will now be described with reference to the annexed diagrammatic drawings, of which:

FIGURE 1 is a sectional side elevation of a jet propulsion nozzle adjusted for rearwards discharge;

FIGURE 2 corresponds to FIGURE 1 but shows the nozzle adjusted lfor forwards discharge; FIGURE 3 is a cross-section taken through the plane 3-3 in FIGURE 1;

FIGURES 4 and 5 are sections taken on a larger scale of part of the actuating rams for adjusting the nozzle, in two different positions of operations;

FIGURES 6, 7, and 8 are side elevations of a second nozzle in different positions; and

FIGURE 9 is a perspective view of the second nozzle in reverse thrust position, looking somewhat aft and downwards, with parts broken away.

Referring to FIGURES 1 and 2, the exhaust gas jet pipe 10 of a jet propulsion gas turbine engine for an aircraft terminates downstream in a jet propulsion nozzle which broadly comprises a fixed convergent nozzle 11, an annular air duct 12 which surrounds the nozzle 11, and a divergent discharge nozzle 13 which normally receives both the gas flow from the nozzle 11 and the air flow from the duct 12. The final nozzle 13, which has a small angle of divergence, is relatively long and is adjustable to vary the nozzle area to suit different operating conditions and to reverse the direction of discharge for braking purposes. The stream of air from the duct 12, which may be boundary layer air tapped from the aircraft wing, flows over the inner surfaces of the nozzle 13 to form a relatively cool protective layer, and is controlled by a ring of joggled flap valves 15 (only one is shown) the operation of which will be described later. v

The final nozzle 13 includes a pair of fixed side wall members 17 forming downstream continuations of the wall 16 of a square-sectioned nacelle. Between the wall members 17 are a pair of double-skinned aps 18. The inner and outer skins 22, 23 of each fiap converge towards one another in the downstream sense, and the crosssection of each inner skin changes from semi-circular at the upstream end to channel section at an intermediate portion and finally to that of a substantially flat plate at the downstream end while the `outer skin 23 is relatively fiat throughout its main length. Each wall member 17 carries a channel-sectioned heat shield 19 which is spaced from the 4inner surface of the member to form therewith a thermally-insulating lateral compartment for the actu- "ice ating linkages of the adjustable fiaps 18. The shields 19 are secured at their upstream ends to an annular bulkhead 20 which extends between the nacelle wall 16 and the air duct 12, upstream of the liaps 18. The downstream ends of the shields 19 terminate short of the outlet plane of the nozzle 13, and thetwo shield-carrying wall mem bers 17 together with the flaps 18 combine to form in normal operation a divergent discharge nozzlewith a final cross-section of generally rectangular shape. Each flap 18 has its inner skin 22 reinforced by longitudinal corrugated stiffeners 25 and spaced from the load-carrying outer skin 23 by a transverse corrugated stiffener 24, Y

which is fixed to the longitudinal stiffeners 25 at one end and is connected to the stiifeners 25 at the other end by a swinging link (not shown) so as to accommodate any relative movement between the gas-swept inner skin and the relatively cool outer skin. At their upstream ends, the flaps 18 are formed with convex part-cylindrical sealing surfaces 23a which normally mate with a concave sealing part 26 carried by the nacelle wall 16, and there is a further part-spherical gas sealing surface 27a on each flap to mate during normal operation with a part-spherical labyrinth gland 27 on the adjacent end of the air duct 12.

Four pneumatic motors 28 for driving the flaps 18 are mounted on the air duct 12, and at their radially outer portions are connected to the nacelle wall 16 by brackets 29. Each motor is geared to a separate recirculating ball nut 30 (see FIGURE 4) for actuation of a screw-threaded main ram 31. The four rams 31 (see' FIGURE 3) are coupled together for synchronised operation through reduction gearing 32 in engagement with a ring gear 33, which is housed in a protective tube 34 mounted on the air duct 12.

Referring to FIGURES 4 and 5, each main ram 31 is surrounded by a tubular `secondary ram 36, which in turn is surrounded by a tubular housing 37 fixed at its upstream end to the "tube 34. The main ram 31 may be locked to the secondary ram 36 by balls 35 lying in holes in the secondary ram. The housing 37 extends rearwards to form a cage for normally retaining the locking balls 35 in their locking position in an annular recess V38 formed in the main ram 31. When the main ram 31 is moved rearwards, towards the end of its stroke a fiange 36a on the secondary ram actually engages the housing, and the locking balls 35 are pushed outwards into internal pockets 39 formed at the rear ends of the housing 37, thus locking the secondary ram 36 to the housing and freeing the main ram 31 from the secondary ram 36 for completion of its stroke. When the recessy 38 reaches the socket 39 on the return stroke of the main ram, a shoulder 31a on the main ram engages the secondary ram and carries it with the main ram.

The flaps 18 are driven by the following mechanism. Taking the mechanism on one side onlyvof the nozzle for convenience, there is an upper motor 28- and a lower motor 28, each of which drives a main ram 31 and a secondary ram 36. The rams pass through apertures in the bulkhead 20 to enter the lateral linkage compartment formed between the adjacent heat shield 19 and wall 17. Each ram has a forked extension 40 supporting a cross pin 41, on which is mounted a short link 42 connected to one end of a coupling rod 43. This extends rearwards in its lateral compartment, and engages at its other end a pin 44, which is mounted on the outer skin of the adjacent flap 18 and projects outwards through a triangular slot formed in the adjacent heat shield 19. Each link 42 is also connected to one apex of a triangular radius plate 45, which is mounted at a second apex on a fixed pivot pin 46 projecting inwards from the'adjacent side wall member 17. Each of the secondary rams 36 has a laterally offset forked extension supporting a cross pin on which is mounted a short link 42a, connected to one apex of a triangular fulcrum plate L17 which is also mounted at a second apex on the pivot pin 46. The remaining and downstream apex ot' the fulcrum plate 417 is engaged by a pin 48 which is mounted on the outer skin of the adjacent flap 18 and projects outwards through a curved slot 49 formed in the adjacent heat shield 19. v

Each of the aps 18 is therefore linked to two motors 23, one on either side of the nozzle, through two pairs of rams 31, 36, two radius plates 45, and two fulcrurn plates 4'7, all of which linkage is protected by the heat shields from contact with the hot exhaust gas. The curvature of the sealing part 26 is centered on the axis of the pins 46, and so long as the main and secondary rams are locked together, operation of the motors 2S will cause the four radius plates, the four fulcrum plates, and the two flaps to pivot about a common upstream axis, constituted by the pins 46, which intersects the nozzle axis, and will cause the pins d8 to move along their respective slots 49 in the heat shields 19 until they reach the inner ends of the slots. VJ'nen the main rams have been unlocked from the secondary rams and the latter together with the fulcrum plates 47 have become locked to the stationary structure through the housings 37, continued operation of the motors will then cause the flaps 18 to pivot about downstream parallel axes'constituted by the pairs of pins 48, so that their sealing surfaces 23a disengage completely from the sealing part 26 and their downstream ends swing inwards to contact one another and form a V-type flow reverser as shown in FIGURE 2.

The initial pivotal movement of the flaps 1d, i.e. the movement about the common axis of the pins 46, results in a variation of the area of the nozzle 13, which may d as to affect substantially the air flow through the duct 1?.. During the next phase, when the aps pivot inwards about the axes of the pins 418, the valve ring is axially displaced progressively more, and the valves are caused to approach their fully shut position. Finally, as the flaps complete the movement to their thrust-reversal position shown in FIGURE 2, the rate of displacement of the valve ring is reduced, so that the final closing movement of the valve is a gentle one to avoid a damaging impact with the inner wall of the air duct 12.

lt will be seen therefore that the pivotal movement of the flaps about the upstream axis which intersects the centre line of the nozzle enables the area of the final section of the nozzle to be reduced but does not open up the lateral outlets. The pivotal movement of the daps about the downstream axes of the pins d8' brings them to their thrust reversal positions in which they provide reverse flow outlets which are suiiiciently large to accommodate the full gas dow, the outlets being bridged by the grids of l stream of the corrugations, in order'to permit them to even change it from divergent (considering cross-sectional engine operation, and during this movement the seal between the surfaces 27a of the flaps and the labyrinth gland 27 on the air duct remains unbroken, so that the propulsive liow cannot escape laterally but is constrained to flow rearwards through the nozzle passage.

Two oblong grids of guide vanes 50, which are normally located in upper and lower recesses between the air duct 12 and the nacelle wall, are connected by pin joints to the upstream ends of the ilaps 18. The grids, which are provided with side plates 51, are movable along pairs of curved guide tracks 52. When the liaps 18 are made to pivot towards one another about the downstream axes of the pins 48, two opposing lateral outlets 53 are formed upstream of the iiaps, and at the same time the grids 5d are pulled out of their recesses by the aps, the grids travelling along the guide tracks 52 until they lie across the outlets 53 to guide the discharge of the gas ilow which has been deected forwards and outwards by the ilaps in their dow-reversal position.

During flow-reversal, it is necessary to prevent a forwards ow of reversed gas through the air duct 12 and for this purpose the ring of curved and joggled flap valves 15 is provided. Each valve 15 is hinged to the outer wall of the air duct 12 and is connected by a system of forked levers 55, 56 and trunnion blocks 57 to a common valveoperating ring 5S which is movable axially. A torsion bar (not shown) is provided in each valve spindle to accommodate thermal distortion and manufacturing tolerances. Each yof the four radius 'plates 45 carries a pin dil which is connected by an arm 61 to one end of an adjustable rod 62, the other end of which is pin-jointed to the valve ring 5S. A radius rod 63 anchors one end of the rod 62 to a iixed stud ed which is mounted on the adjacent nozzle wall member 17.

As seen in FIGURE l, the arrangement of the valveoperating linkage is such that during the initial pivotal movement of the flaps 18 about the pins i6 the accompanying movement of die radius plates results in little or no axial displacement of the valve ring 51%.y Consequently during the movement of the flaps to vary the area of the divergent nozzle, the valves 15 are not operated so control effectively the iiow of air through the annular duct.

In the second nozzle, shown in FIGURES 6 to 9, the operating mechanism is somewhat simpler. As in the first nozzle, there are two iixed wall members 85, and two channel-shaped adjustable aps 86. Each wall member is formed by two spaced skins. Associated with each flap is a grid 92 of guide vanes, and the grids serve as members of a linkage by which the flaps are operated.

At each side of the nozzle is a fixed housing 1% within which is a ram serving to move two lugs 109 forwards and rearwards. The rams are both in the form of screw jacks and are driven by a single air motor (not shown) via shafts in casings 1413. The housings 106 provide ixed pivots on which are mounted V-shaped hoops 115. Thus each hoop pivots on a transverse axis which extends across the nozzle and adjacent to the longitudinal centre line of the nozzle.

The hoops are connected to the lugs 109 by links 111. Each grid 92 has a frame 124, which is pivoted at 125 to both sides of the flap 86, and which is pivoted at 121 to both sides of the hoop. Thus the rams in the housings 1% can urge the flaps 86 forwards or backwards, while sideways sway or twisting of the flaps is resisted.

Each flap is guided at both sides by a projection 136 engaging in a cam track S3, and by a radius link 129. Each projection is in the form of a ball race on a stud xed at 133 to the fixed wall member 85. Each cam track is a groove in the thickness of the side of the flap 86. Each link 129 lies mainly in the compartment between the two skins forming the ixed wall member 85, passing into the compartment through a slot 130, and is pivoted at its upstream end 127 to the rear end of the fixed ram housing 106. At its downstream end, the link is pivoted to the side of the fiap 86 by a pin 128 which passes through a slot 93 in the inner skin of the fixed wall member and has a tiange at its inner end which is bolted to the flap.

The successive positions of full thrust, reduced thrust, and reversed thrust are shown in FIGURES 6, 7, and 8 respectively. Each groove 83 is generally V-shaped with its apex outwards. The downstream limb 88a of the groove is curved and, in the position of FIGURE 6, is concentric with the pivot 127. Consequentlythe movement of the tiap from FIGURE 6 to FGURE 7 is a pure rotation about an upstream pivot axis through the pivots 127. The upstream limb S817 is a curve designed to guide the flap to the position shown in FIGURE 8. Itis nearly, but not exactly, an arc centred on the pivot 128. Thus the flap turns about a downstream axis, but this axis is not exactly through the pivots 128, and indeed the instantaneous axis of rotation of the flap may shift somewhat during this turning movement.

The ixed wall members are connected by bridge plate S9. The bridge plates has slots through which the grids pass when moving downstream towards the position shown in FIGURE 8. When each grid reaches the position shown in FIGURE 8 a cross-plate 126 at the upstream end of the grid engages the bridge plate 89 and closes the slot so as to prevent hot gases from passing forwards through the slot. The shape of the downstream limb 88a of the groove 88 is such that the grid moves along a relatively at curved path through the slot thus permitting the vertical dimensions of the slots and bridge plate and therefore of the engine nacelle at that location to be reduced as much as possible.

The nozzle receives gas flow from a gas duct having inner and outer skins 81, 82, between which is an annular air duct, controlled by an annular series of ilap valve 80. These valves are operated by the hoops 115, through linkages 117, 118, 119. The ram housings 106 are mounted on the outer skin 82 of the gas duct.

The hoops straddle the air duct and are thus in a relatively cool situation. Around the hoops is a iixed casing 83.

We claim:

1. A jet propulsion nozzle including fixed structure, and a pair of opposing flaps which dei'ine between them a nozzle passage leading to a rear outlet, means carried by said ixed structure and operatively connected to said flaps mounting said ilaps for pivoting movement about an upstream axis and for pivoting movement about a dov/nstream axis at a fixed distance from the upstream axis, said axes being spaced a substantial distance apart in the fore-and-aft direction, whereby said flaps are mounted in the fixed structure to pivot each about its respective upstream axis to vary the cross-sectional area of the nozzle passage, and, as a separate operation, to pivot each about its respective downstream axis to reach a position in which the flaps deiine with the fixed structure a pair of closed, and which are pivotably connected to the respective flaps.

3. A nozzle according to claim 2, including a gas duct arranged to direct gas flow rearwards into the upstream end of the nozzle passage, in which the pivotably mounted members are substantially U-shaped and straddle the gas duct and each grid is pivoted to both sides of the middle portion of the respective U-shaped member and to both sides of the respective flap.

4. A nozzle according to claim 3, in which the ends of each U-shaped member pivot on a transverse axis which extends across the nozzle and adjacent to the longitudinal centre line of the nozzle.

5. A nozzle according to claim 3 in which the gas duct has inner and outer skins between which is an annular air duct, the U-shaped members are pivotably mounted on the outer skin and the air duct is controlled by valves which are connected by operating linkage to the U-shaped members.

References Citedin the le of this patent UNITED STATES PATENTS 2,620,622 Lundberg Dec. 9, 1952 2,874,538 Laucher et al Feb. 24, 1959 2,950,595 Laucher et al Aug. 30, 1960 2,976,676 Kress Mar. 28, 1961 3,015,936 Brewer et al Jan. 9, 1962 3,024,605 Nash Mar. 13, 1962 

1. A JET PROPULSION NOZZLE INCLUDING FIXED STRUCTURE, AND A PAIR OF OPPOSING FLAPS WHICH DEFINE BETWEEN THEM A NOZZLE PASSAGE LEADING TO A REAR OUTLET, MEANS CARRIED BY SAID FIXED STRUCTURE AND OPERATIVELY CONNECTED TO SAID FLAPS MOUNTING SAID FLAPS FOR PIVOTING MOVEMENT ABOUT AN UPSTREAM AXIS AND FOR PIVOTING MOVEMENT ABOUT A DOWNSTREAM AXIS AT A FIXED DISTANCE FROM THE UPSTREAM AXIS, SAID AXES BEING SPACED A SUBSTANTIAL DISTANCE APART IN THE FORE-AND-AFT DIRECTION, WHEREBY SAID FLAPS ARE MOUNTED IN THE FIXED STRUCTURE TO PIVOT EACH ABOUT ITS RESPECTIVE UPSTREAM AXIS TO VARY THE CROSS-SECTIONAL AREA OF THE NOZZLE PASSAGE, AND, AS A SEPARATE OPERATION, TO PIVOT EACH ABOUT ITS RESPECTIVE DOWNSTREAM AXIS TO REACH A POSITION IN WHICH THE FLAPS DEFINE WITH THE FIXED STRUCTURE A PAIR OF OPPOSING LATERAL OUTLETS FROM THE NOZZLE PASSAGE FOR THE DISCHARGE OF A GAS FLOW IN A DIRECTION HAVING A COMPONENT THE REVERSE OF REARWARD, AND IN WHICH THE FLAPS CLOSE THE REAR OUTLET BETWEEN THEM. 